while虽然引导什么从句

　　例句：

　　After lunch, she likes to take a nap for a while.

　　她喜欢午饭后眯一会儿。

　　It takes a while to adapt to a new environment.

　　适应新环境需要花一段时间。

　　We must strike while the iron is hot.

　　趁热打铁。我们必须当铁热的时候去击打它。

　　While he is speaking, he does a lot of gestures.

　　他演讲的时候有很多手势。